The invention is related to a device for cleaning large quantities of water and rakings at overflow edges. In different applications the necessity arises to sieve and clear rakings of large quantities of water. When, for instance, a large quantity of cooling water is to be taken from a river, an overflow edge is usually created, and the overflowing water is used. This should, depending on the requirements, be free of matter ranging from rakings to suspended particles. Local sewage technique also has the problem to sieve large quantities of water, especially during and after the event of a heavy rain, e.g. a thunderstorm. Then a large quantity of water is accumulated in a relatively short time, which the sewage plant is not designed to cope with. Rain reservoirs and rain overflow basins are then used, to store the surplus quantity of water intermediately and to work it off after the end of the rain event. But such rain reservoirs also have a limited capacity, which in some cases will be exceeded, so that the surplus water will then be routed e.g. into a river untreated. Especially during such thunderstorms or after dry weather periods the water carries a lot of dirt that should be separated off.
A device of the above described type is known from the German Offenlegungsschrift 40 37 884. The separation area is formed to be a section of a cylinder jacket and arranged with its axis lying parallel to the overflow edge. The separation area extends over about 90.degree. of tile cylinder jacket, and the axis of the cylinder jacket is provided a distance corresponding to about the radius of the cylinder jacket below the overflow edge, so that the water flowing over the overflow edge is supplied at about the highest point of the cylinder jacket. The separation area is thereby limited in area, and there is the danger that after a blocking of the separation area the water will flow over the device into a drainage channel untreated. A takeover device, which is driven about the axis of the cylinder jacket, is assigned to the separation area for removing the rakings separated at the separation area. The takeover device is driven by the overflowing water itself, so that the drive is dependant on the water level above the overflow edge. At a low water level there is the danger that the takeover device is not driven anymore. At a high water level there is the danger that the separation area, which is limited in area, is blocked quickly and that the following water flows over it untreated.